His works, accomplished mostly in small format, represent rococo and transition to early classicism. In the Russian Empire, in an area that is now Estonoia, he painted figural staffages on large Põltsamaa landscapes and depicted Estonian peasants in the 1780s; in Mainz and Frankfurt-am-Main he was known mostly as an etcher and a landscapist. Welté was a typical artist of the Enlightenment – pensive, developing and nonconformist.[2]
His most important work, the illusionist fresco wall paintings in the hall of the Lohu manor covering 27,6 m2, were discovered in the 1960s under the Grisaille pictorial fresco wall papers on the theme of Don Quixote, printed by "Jacquemart & Bénard" in Paris, France.[4]